化学掺杂可有效提高共轭聚合物（CP）的电学性能，其中次序掺杂是一种常用的化学掺杂方法。在次序掺杂的相关研究中，人们一般通过调控预制CP薄膜的结晶结构来提升其电导率，鲜少关注使用不同溶剂配制掺杂剂溶液对CP掺杂性能的影响。目前人们主要选用CP的正交溶剂来配制掺杂剂溶液，尚未有CP的良溶剂在次序掺杂CP过程中起“正向”作用的报道。聚（3-己基噻吩）（P3HT）结构简单、容易结晶、电学性能较好，可制备有机场效应晶体管（OFET）、有机太阳能电池（OSC）、有机发光二极管（OLED）等光电器件，是人们研究CP结构与性能关系的模型材料。本文选择2,3,5,6-四氟-7,7',8,8'-四氰二甲基对苯醌（F4TCNQ）作为掺杂剂，使用P3HT的良溶剂氯苯（CB）和正交溶剂乙腈（AN）的二元混合物作为掺杂剂溶剂，通过次序掺杂法掺杂预先制备的P3HT薄膜，主要研究内容和成果包括以下几个方面：

首先，我们研究了良溶剂CB对P3HT薄膜掺杂性能的影响。结合紫外-可见-近红外（UV-vis-NIR）光谱、掠入射X射线衍射（GIXRD）、傅里叶变换红外（FTIR）光谱、原子力显微镜（AFM）及四探针测试，我们发现用F4TCNQ的CB/AN混合溶剂溶液次序掺杂P3HT薄膜时，良溶剂CB可以溶解薄膜中的非晶态P3HT，使其在溶液中与F4TCNQ掺杂形成结晶性聚集体。这些结晶性聚集体有效地“桥接”P3HT薄膜的结晶区域，形成逾渗结晶网络，有助于电荷载流子传输，从而使P3HT掺杂薄膜的载流子迁移率和电导率高于从纯AN溶液中次序掺杂的薄膜。随着CB含量的增加，结晶性聚集体的数量增加；另一方面，CB良好的溶解能力会破坏P3HT薄膜中的结晶部分，抑制载流子传输。桥连晶区效应和溶解破坏效应的综合作用导致P3HT掺杂薄膜的载流子迁移率和电导率先随CB含量的增加而增加，然后随CB含量的进一步增加而降低。这项工作证实了化学掺杂CP时次序掺杂的同时可伴随溶液掺杂。我们对P3HT掺杂薄膜的拉伸性能进行了测试，结果表明掺杂不会显著降低P3HT薄膜的拉伸性能。精确调控F4TCNQ溶液中良溶剂与正交溶剂的比例以及预制P3HT薄膜的制备条件，可以获得兼具良好电学性能和拉伸性能的P3HT薄膜。

随后，我们研究了以上F4TCNQ掺杂的P3HT薄膜的稳定性，结果表明P3HT掺杂薄膜不稳定，即使在无水无氧避光环境下也会发生解掺杂，导致电导率下降。纯AN溶液掺杂的P3HT薄膜在解掺杂过程中迁移率基本不变，电导率降低是整数电荷转移（ICT）掺杂结构分解造成的，电导率衰减速率较慢。CB/AN混合溶剂溶液掺杂的P3HT薄膜解掺杂过程中，在CB溶液中生成的结晶性聚集体分解为非晶部分，桥连作用消失，ICT掺杂结构分解的同时迁移率也迅速降低，导致电导率衰减速率较快。我们发现在P3HT薄膜的解掺杂过程中，有序性高的ICT掺杂结构分解速率更快。此外，解掺杂过程掺杂薄膜中生成了新的结构，我们推测为中性F4TCNQ。

此外，我们研究了F4TCNQ溶液浓度对次序掺杂的P3HT薄膜性能的影响，结果表明增加F4TCNQ溶液浓度会增加P3HT薄膜中ICT掺杂结构的含量，提高薄膜电导率。在CB/AN混合溶剂体系中，掺杂剂浓度低时，倾向于在CB中发生溶液掺杂，但CB的溶解破坏作用大于桥连晶区作用，导致P3HT掺杂薄膜的迁移率低于纯AN溶液掺杂的；随着掺杂剂浓度的增加，次序掺杂占比增加，当掺杂剂浓度高于0.2 mg mL^-1时，CB桥连作用占优势，P3HT掺杂薄膜的迁移率高于纯AN溶液掺杂的薄膜迁移率。

最后，我们选用P3HT的正交溶剂二氯甲烷（DCM）与CB配制不同比例的混合溶剂，将F4TCNQ溶解于CB/DCM混合溶剂中次序掺杂P3HT薄膜，得到了与CB/AN混合溶剂掺杂体系相似的实验结果，表明使用P3HT的良溶剂与正交溶剂混合配制掺杂剂溶液并次序掺杂P3HT以有效提高P3HT掺杂薄膜的电导率的方法适用于多种正交溶剂，具有一定的普适性。

Chemical doping can effectively improve the electrical properties of conjugated polymers (CPs), and sequential doping is a commonly used chemical doping method. In the related research on sequential doping, people have improved the electrical conductivity of prefabricated CP films by adjusting the crystalline structure, and little attention has been paid to the effect of dopant solutions prepared with different solvents on CP doping properties. At present, people mainly choose the orthogonal solvent of CP to prepare the dopant solution, and there is no report about the good solvent of CP playing a "positive" role in the process of sequential doping of CP. Poly(3-hexylthiophene) (P3HT) is simple in structure, easy to crystallize, and has good electrical properties, which can be used to prepare photoelectric devices such as organic field-effect transistors (OFETs), organic solar cells (OSCs) and organic light-emitting diodes (OLEDs). It is a model material for people to study the relation of structure and properties of CP. In this paper, 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanodimethyl-p-benzoquinone (F4TCNQ) was selected as the dopant. Chlorobenzene (CB), a good solvent for P3HT, and acetonitrile (AN), an orthogonal solvent for P3HT, the blends of which two was used as the dopant solvent to dope the prefabricated P3HT films by sequential doping method. Our main research contents and achievements include the following aspects:

    First, we investigated the effect of good solvent CB on the doping properties of P3HT films. Combining the results of ultraviolet-visible-near-infrared (UV-vis-NIR) spectroscopy, grazing incidence X-ray diffraction (GIXRD), Fourier transform infrared (FTIR) spectroscopy, atomic force microscopy (AFM) and four-probe tests, we found that when the P3HT films were sequentially doped with the CB/AN mixed solution of F4TCNQ, the good solvent CB could dissolve the amorphous P3HT in the film and make it doped with F4TCNQ in solution to form crystalline aggregates. These crystalline aggregates effectively "bridge" the crystalline regions of P3HT films to form a percolation crystallization network that facilitates charge carrier transport, resulting in higher carrier mobility and electrical conductivity of these doped P3HT films than those of sequentially doped films from pure AN solution of F4TCNQ. With the increase of CB content, the number of crystalline aggregates increases; on the other hand, the good solubility of CB will destroy the crystalline regions in P3HT films and inhibit the transport of carriers. The combination of bridging crystalline regions effect and dissolution destruction effect results in the carrier mobility and conductivity of the doped P3HT films first increasing with increasing CB content and then decreasing with further increasing CB content. This work demonstrates that sequential doping can be accompanied by solution doping when chemically doping CP. We tested the tensile properties of the doped P3HT films, and the results showed that the doping did not significantly reduce the tensile properties of the P3HT films. By carefully adjusting the ratio of good solvent to orthogonal solvent in F4TCNQ solution and the preparation conditions of prefabricated P3HT films, P3HT films with both good electrical and tensile properties can be fabricated.

    Subsequently, we investigated the stability of the above F4TCNQ-doped P3HT films, and the results showed that the P3HT-doped films were unstable, and dedoping behavior occured even in an anhydrous, oxygen-free and light-free environment, resulting in a decrease in electrical conductivity of doped films. The mobility of P3HT thin films doped with pure AN solution of F4TCNQ was basically unchanged during the dedoping process. The decrease in conductivity of this system was caused by the decomposition of the integer charge transfer(ICT)-doped structure, and the conductivity decay rate was slow. During the dedoping process of the P3HT films doped from CB/AN mixed solution of F4TCNQ, the crystalline aggregates generated in CB decomposed into amorphous parts, the bridging effect disappeared, the ICT-doped structure was decomposed and the mobility also decreased rapidly, resulting in faster conducticity decay rate of films. We found that the higher ordered ICT-doped structure decomposed faster during the dedoping process of P3HT films. A new structure was generated in the dedoped P3HT film, which we speculate to be neutral F4TCNQ.

    Besides, we investigated the effect of F4TCNQ solution concentration on the sequentially doping properties of P3HT films, and the results showed that increasing the concentration of F4TCNQ would increase the content of ICT-doped structures, and improve the film conductivity. In the CB/AN mixed solvent system, solution doping in CB easily occurs when the dopant concentration is low, but the dissolution and destruction of P3HT by CB is greater than the effect of bridging crystal regions, so the mobility of P3HT films doped from CB/AN mixed solvent was lower than that from pure AN solvent; with the increase of dopant concentration, the proportion of sequential doping becomes larger, when the dopant concentration is higher than 0.2 mg mL^-1, the bridging effect is dominant, and the mobility is higher than the the mobility of P3HT films doped from pure AN.

    Finally, we used dichloromethane (DCM), an orthogonal solvent for P3HT, and CB, to prepare mixed solvents in different proportions. F4TCNQ was dissolved in the mixed solvent of CB/DCM, and then sequentially doped P3HT films. We obtained the experimental results similar to those of the CB/AN mixed solvent doping system, indicating that sequentially doping P3HT films with a dopant solution prepared by mixing a good solvent of P3HT with an orthogonal solvent can effectively improve the electrical conductivity of doped P3HT films. This method is suitable for a variety of orthogonal solvents, and it has certain universality.